The present invention relates to improvement in a distributed feedback semiconductor laser.
The distributed feedback semiconductor laser (hereinafter referred to simply as the "DFB laser") readily operates at a single wavelength even under high-speed modulation, and hence is now being expected to be used as a light source for use in long-distance, large-capacity optical fiber communications. However, it is very difficult to provide in accordance with conventional art a DFB laser capable of stably operating at a single wavelength as mentioned below.